1. Field of the Invention
The present invention relates to the discovery of a specific class of plasticizers for poly(iminoimidazolidinediones) and poly(parabanic acid) resins.
Related Art
Both the poly(iminoimidazolidinediones) and poly(parabanic acids) and their methods of preparation are known and described in detail in commonly assigned U.S. Pat. No. 3,661,859, which is incorporated in its entirety herein. The poly(parabanic acids) may also be prepared by other processes, such as shown in U.S. Pat. No. 3,609,113.
The poly(iminoimidazolidinediones) may be formed by the reaction of hydrogen cyanide with a diisocyanate or mixture of diisocynates, the reaction of a dicyanoformamide with a diisocyanate or mixtures of diisocyanates, or the polymerization of a cyanoformamidiyl isocyanate and contain a 1,3-imidazolidinedione-1,3-diyl ring of the following structures in the repeat units: ##STR2## wherein NH is in the 4 or 5 position.
The poly(parabanic acids) also designated as poly(1,3-imidazolidine-2,4,5-triones) may be prepared, for example, by the acid hydrolysis of poly(iminoimidazolidinediones) and contain the imidazolidinetrione ring in the repeat unit: ##STR3## U.S. Pat. No. 3,609,113 and German Pat. No. 1,770,146 describe other methods for preparing polymers which contain the poly(parabanic acid) ring.
The polymers may contain both imino-1,3-imidazolidinedione-1,3-diyl rings and imidazolidinetrione rings, thus the present polymers may be broadly characterized as having the repeating unit: EQU --Q--R].sub.n
wherein Q is ##STR4## wherein X is 0 or NH, provided that at least one X is 0, R is an organic moiety which may be aliphatic, alicyclic, aromatic or mixtures thereof, and n is sufficiently large to produce a solid product.
The R is the organic moiety of the diisocyanate when the polymer is produced according to the procedure in U.S. Pat. No. 3,661,859. Thus, the diisocyanates may be selected from a broad group having a large variety of organic moieties. The organic moieties of the diisocyanate may be substituted with groups such as alkyl, aryl, halogens, sulfoxy, sulfonyl, alkoxy, aryloxy, oxo, ester, alkylthio, arylthio, nitro and the like which do not react with the isocyanate group. Functional groups which have active hydrogen atoms, (e.g., carboxylic acids, phenols, amines, etc.) should not be present. Specific diisocyanates which may be used are set out in the U.S. Pat. No. 3,661,859, other patents, articles or organic textbooks as known in the art.
Some of the parabanic acid polymers have been found to have high glass transition temperatures, and thus are especially suitable as magnetic tapes (where good dimensional stability at high temperatures is required), films for use in flexible printed circuits, cable wraps, etc., for fibers such as tire cord fibers (where tensile strength and modulus are required), for moldings for electrical connectors, bearings, magnetic wire insulation, coatings for cables, cookware, glass fabrics, industrial belts (where high temperatures are required) and the like.
However, many of the present polymers decompose when they are heated at or above their glass transition temperatures and as a result they can not be molded or extruded. Previously these polymers could be processed only by solution methods or by a powder coating technique which also requires a solvent.
It is an advantage of the compositions of the present invention that the poly(iminoimidazo-lidinediones), poly(imidazolidine-2,4,5-triones) or mixed poly(iminoimidazolidine-1,3-dione/imidazo-lidine-2,4,5-triones) or as defined above the polymers --Q--R].sub.n may be processes by extrusion and molding techniques, when plasticized according to the present invention. Also films of the compositions of the present invention can be heat-sealed whereas films of the same pure polymers can not be sealed with heat. It is a particular advantage of some of the present plasticizers in that they are not detrimental to polymers which contain small quantities of a copper chelate for thermo-oxidative stability; many other materials investigated as plasticizers do adversely effect the thermal stability.
Various polymeric materials have been plasticized with various aromatic ketones. For example, U.S. Pat. No. 3,300,438 discloses polyvinyl chloride plasticized with methyl substituted benzophenone; U.S. Pat. No. 3,328,336 similarly discloses polyvinyl acetate plasticized with alkylated benzophenone and U.S. Pat. No. 4,184,994 discloses polycarbonates plasticized with ketones. German Pat. No. 2,513,779 discloses dibenzofuran and 9-fluorenone derivatives as plasticizers for plastics. U.S. Pat. No. 4,228,066 discloses the copper chelates of 2-hydroxybenzophenones as UV stabilizers for poly(parabanic acid, in small amounts, of about 0.1 to 3.0 weight % based on the weight of polymer which are too low to permit the 2-hydroxybenzophenones to function as plasticizers.